Metal-bending machines



Dec. 11, 19576 A. M. REDMAN METAL-BENDING MACHINES 2 Sheets-Sheetl lFiled March 30 1955 ,wrm/Vars United States Patent O 2,773,531METAL-BENDING MACHINES Albert Maurice Redman, Worcester, England,assignor to Redman Tools & Products Limited, Worcester, England, aBritish company Application March 30, 1953, Serial No. 345,437 7 Claims.(Cl. 153-46) This invention comprises improvements in or relating tometal-working machines, and relates to methods of and machines forbending and shaping metal bars, strips, rods and like work pieces. InBritish patent specifica-y tions Nos. 655,560 and 661,041 and thecorresponding U. S. Patents No. 2,636,537 and No. 2,680,487,respectively, there are described metal bending machines each comprisingthe combination of a curved former, means to hold the workpiece in placeagainst the former for shaping, a shoe capable of rolling upon theworkpiece against the former, a iluid-pressure-operated ram or itsequivalent to press the shoe, workpiece and former together, and meansto effect rolling of the shoe against the former, while theram pressureis maintained to shift the place of application of pressure to theworkpiece progressively along its surface, the means to hold theworkpiece in place serving to clamp against the former one end of thepart to he bent and the shoe moving during the bending operation in adirection to shift the place of application of pressure to the workpieceaway from the clamped end; the present invention relates to machines ofthis type.

Such machines have made it practicable to produce, by cold bending,curved forms which it was hitherto thought virtually impossible toobtain.

However, with the machines according to British patent specificationsNos. 665,560 and 661,041 and conforming to the above type, there is alimit to `the complexity of the curved forms which can be produced dueto the fact that during the bending operation the free unformed part ofthe workpiece beyond the nip between shoe and former tends to wrinkleand distort or wind out of line with the former as the shoe rolls, ifthe desired curve is too sharp or the form is too complicated.'Particularly is this so if the workpiece to be formed is a flangedworkpiece with flanges along both edges, one of which anges is of muchthicker or wider section-than the other; the diierence in width of theflanges tends to result in the workpiece pulling to one side out of linewith the former during the bending operation. 'i

According to the present invention, in ametal-bending machine of thetype described there is provided, on the side of the nip between shoeand former towards which bending proceeds, a supplementary work-holdingmember which supports the workpiece against becoming misaligned withrespect to the former while being bent. v

In the preferred construction, the 'supplementary work-holding member iscarried by the shoe, being mounted to be movable along it, said'memberbeing in slidable engagement with the workpiece during bending andactuating means, such as a fluid-operated piston-andcylinder unit, isprovided operatively connected to the supplementary work-holding memberto move it along the shoe and workpiece ahead of the place ofapplication of pressure to the workpiece as the latter advances andthereby to keep it clear of the nip between shoe and former.

Preferably, the supplementary work-holding member is mounted to slidealong the forming surface ofthe shoe and is spaced from said surfacesuiciently'to allow a workpiece to pass between the supplementaryworkholding membervand the shoe while being held closely L Mice againstthe shoe by the supplementary work-holding member. Thus, in the casewhere the forming surface of the shoe is concave in the cross-sectionalplane at right angles to the plane of movement of the shoe (the formerbeing correspondingly convex) thereby constituting a channel along theshoe, the supplementary work-holding member may be mounted to slidewithin the channel.

One form of bending machine constructed in accordance with the inventionwill now be described by way of example and with reference to theaccompanying drawings in which:

Figure l is a plan view of the machine, and

Figure 2 is an enlarged perspective view of part of the machine, lookingslightly downwards and in the general direction of the arrow 2 of Figure1, showing one end of the bending shoe of the machine, and also showingthe supplementary work holding member in partially withdrawn position.

The machine is primarily for forming motor car bumpers and is, ingeneral, similar to that described in British patent specification No.665,560, having a heavy main frame l1 upon' which is secured a fixedmale former 12 with a convexly curved profile 15 as considered in planview, and an arm 13 mounted to swing upon the frame 11, in a horizontalplane about a pivot 14 located behind the former profile, which arm 13spans the former 12 and carries beyond the convex profile 15 a hydraulicpiston-and-eylinder unit 16 with its piston rod 31 extending towards theformer, the axis of said unit lying in the horizontal plane bisectingthe former.

Between the piston-and-cylinder unit 16 and the former there is a shoe17 for shaping the workpieces, which shoe is in the `forni of a mildsteel block about three feet long and with a cross-section about a` footsquare; this shoe rests upon a horizontal table 18 over which it is freeto slide and which forms part of the swinging arm 13. The piston rod ofthe piston-and-cylinder unit has a roller nose 19 to bear upon the backof the shoe 17 and press it against the former. The former prole 15 isshaped, in vertical cross-section, to suit the internal form of themotor car bumper it is desired to produce, and the front face of theshoe has a longitudinal recess or channel 20 on a level with the formerprole and shaped in crosssection in accordance with the required outsideform of the bumper so that it constitutes a movable female former tomate with the fixed male former in shaping the workpiece. n

In addition to the main piston-and-cylinder unit 16 carried on theswinging arm 13 `for applying pressure to the yback of the shoe 17,there is an auxiliary piston-andcylinder unit 2l to Igive a further`degree of control over the movements of the shoe, as described inBritish patent specification 665,5 60. .The auxiliary unit `has itscylinder pivoted at one end to a carrier 22 mounted to Islide alongsidethe swinging arm 13 in unison with the piston rod of the main unit r16,and extends `from 4said pivotal connection toward lthe back of the shoeat ,an angle `to the arm 13 and main unit, las viewed in plan. Thepiston rod of the auxiliary unit is connected lthrough a .pin-andslotconnection 23 `whichallows .a certain amount of lost motion `in `adirection substantially parallel rto the axis of the unit to one end of'a saddle 24 mounted to slide in 'a lhorizontal direction upon 1guidesalong the back of the shoe 17. The places of action of 'the main :andauxiliary [piston-and-cylinder units upon the back of the shoe are thus`spaced Itherealong so that lthe, units may be employed to controltheslewing ofthe shoe.

The channel 20 in the `front of the shoe 17 constituting the fem-aleformer is provided -with hardened steel liners. A hardened form-block orsupplementary work holding member 25 is Vlocated within the channel, andarranged to slide therealong, having at its upper an'dlower faces a pairof male guide members or tenons 26 which run in corresponding guideslots 27 fori-ned in the liners 23 constituting the walls of thechannel. The guide slots 27 extend from about midway along the shoe tothe end of the shoe which is nearer the place of action of the auxiliarypiston-and-cylinder unit 21 than that of 'the main unit 16 and the path-of travel of the lform-block extends for a corresponding distance. Tothe end of the shoe at which the guide slots terminate are bolted a pairof vertically spaced ybrackets 124, extending horizontally out -frornthe end face of the shoe, and forming trunnion mounting for one end of ahydraulic pistonand-cylinder unit 29 for controlling the movement of theform-block 25. kThe cylinder of the unit extends from the -trunnionmounting toward the shoe and form-block` and has a pistonrod passinginto the channel 20 of the shoe and pivotally connected to theform-block.

The form-block 25 is ground on its inner surface facing the channelwalls to a lconvex shape in accordance with the cross-section or themale former 12, that is, correspending to the inside shape of the'finished workpiece, so that there is a gap yat 33 `between said innersurface of the forrmblock and the channel walls, which is equivalent tothe `thickness of the metal of a workpiece.

in operation, a straight workpiece, having a shape in t cross section ofthat -desired in the finished bumper, has one end held to the fixed maleformer 12 by means of 'a hydraulically-operated clamp 34. Since theworkpiece is straight, and the former profile is convex, the Itwo areonly in contact for a short distance near the point of clamping. Withthe main `and auxiliary piston-.and-cylinder units for controlling theshoe retracted, fthe arm 13 carrying the shoe 17 is swung ito a position(Figure l) in which the `main hydraulic unit 16 is in line with the partof the workpiece lying close up to the clamped end thereof (it will beseen that the workpiece is so clamped to the male former 12 that, withthe arm 13 in this position, the clamped end is on the opposite side ofthe axis ot the main hydraulic unit 16 to that on which the auxiliaryshoe-control hydraulic unit 21 lies, while the tree unclamped end is onthe same side as said auxiliary unit) and the shoe 17 is positioned sovthat its end remote from the hydraulic cylinder 29 controlling Itheformblock 25 thereon lies between the roller nose 19 of the mainhydraulic unit 16 and said part of the workpiece adjacent the clamp 34,.the remainder of the shoe extending away from the clamped end on thefar side therefrom of the axis of the main hydraulic unit.

The working cycle is now ready to start, and the machine is switched on.Pressure is applied to the back of the shoe 17 by means of the mainhydraulic unit 16 so that the shoe is forced toward the former 12 anddriven tightly on to it laround the workpiece over a limited area inline with the taxis of the main hydraulic cylinder. Since the workpieceis straight and its outer shape corresponds to the female profile of thechannel 20 in the shoe, it iits snugly over its whole length (except forthe clamped end beyond the shoe) into the bottom of the channel in ltheshoe when the shoe is moved on to the male former. At this stage thehydraulic piston-and-cylinder unit 29 controlling the form-block 25 inthe shoe channel 20 is in the retracted position, so that `theform-block is drawn right up to the end of the channel, tand since theshoe is a little longer than the unclamped part of the workpiece to bebent, the form-block 25 is clear of the unclamped end of the workpiece,:and does not interfere with the snug fitting thereof into the shoechannel.

Bending of the workpiece is now ready to commence, and at this point amicro-switch is operated, `by the relative `movements of .the machineparts, which actuates a solenoid-controlled vialve admitting hydraulicpressure to the head end :of the form-block operating cylinder 29, andthereby causes the form-block 25 to slide along the shoe channel 20 tothe opposite end of its travel. In doing so, the form-block passes infront of the workpiece,

and traps it between the block and the walls of the channel 20. At thesame time, the arm 13 carrying the table 13 on which the shoe 17 restscommences to swing slowly in the direction away from the clamped end ofthe workpiece; in the embodiment illustrated the means for swinging theyarm 13 consists of a horizontal hydraulic piston-and-cylindertraversing unit 32 pivotally connected to the arm as described inBritish patent specification No. 665,560 but lalternatively the pivot 14of the arm may be arranged to be bodily movable as described in Britishpatent specification No. 661,041. As the arm 13 swings, the shoe 17begins to slide on its table 18, and the roller nose 19 of the mainhydraulic unit 16 travels along Ithe back of lthe shoe toward the otherend thereof, causing the shoe to roll slowly along the workpiece andaround the lengthwise curve of the Am'ale former 12, swinging angularlyas it does so, but independently of the arm, so thait the 4pressure ofthe shoe on the workpiece is transferred or 'shifts `gradually andprogressively along the workpiece and the metal is progressively `bentaround, and shaped on to, the male former. The auxiliary shoccontrolhydraulic unit 21 may ybe employed .to ensure correct slewing of theshoe, in rel-ation to |the curve of the male former, as described inBritish patent specification No. 665,560.

During the bending operation, after the traversing arm 13 has rotatedthrough a predetermined angular distance the micro-switch associatedwith the form-block-control piston-andcylinder unit 29 is again actuatedautomatically, by the relative movement of the parts, to operate thesolenoid valve and reverse the iiow of pressure Huid to saidpiston-and-cylinder unit, which is of the double-acting type, therebyreversing the movement of the forni-block 25 in the shoe channel 2) sothat it`commences to withdraw toward the end of the shoe. The iiuidiiowing to and from the head end of the cylinder 29 passes through anon-return check valve which allows free liow into the cylinder chamber,but throttles the How leaving the chamber, so that although thefirst-described movement 0f the form-block, which takes place at thecommencement of swinging of the arm to trap the workpiece, is completedrapidly, the withdrawal of the formblock occurs at a slow controlledrate as the bending proceeds. The check. valve is of the needle-valvetype, and the throttle opening may be varied, at will, during theoperation of the machine, by means of a valve control handy to theoperator, to vary the rate of withdrawal of the form-block.

It will be understood that the form-block 25 acts as a supplementarywork-holding member or clamp to control the part of the workpiece whichis not clamped to the male former, that is, the part of the workpiece onthe side of the nip between shoe and former toward which bendingproceeds, and to prevent it from winding or distorting in such manner asto become misaligned with respect to the male former. It is clear thatthe part of the workpiece which is gripped between the form-block 25 andthe walls of the shoe channel 20 cannot become misaligned, despiteforces set up by the bending of a workpiece with flanges of unequalwidth, neither can the part of the workpiece on the side of theform-block remote from the nip between shoe and former at which theactual bending takes place; therefore, for the best operation, theform-block should be kept as close to the nip as it is possible for itto be without actually getting caught in the nip, so as to keep thelength of workpiece between the nip and the work-holding form-block asshort as possible. The form-block must slide along the workpiece aheadof the nip as the place of application of pressure to the workpieceadvances or shifts, and the rate of withdrawal of the form-block. isthus to be controlled in accordance with the speed of rolling of theshoe and the contour of the bent form desired.

Ascan be seen in Figure 1 the space between the shoe 17 and former 12,on the side `of the nip toward which bending proceeds, is acute-angledin plan, and therefore the face 35 of the form-block 25 at the sidenearer the nip makes an acute-angle with the surface of the block facingthe bottom of the shoe channel 20 in order that the block may beintroduced between shoe and former as far as possible toward the nipwithout fouling the shoe or former; the said acute-angle face 35 is alsoground to a form corresponding to the cross-section of the male formerprofile for the same purpose. ln this manner, the workpiece laterallyapproaches the nip from a place close by at which it is held in controlbetween the formblock and the shoe, and distortion is thereby obviated;the form-block keeps control of the workpiece during the bending untilit clears the end of the workpiece, when only a small portion is leftunbent, which is insuicient to distort to any material degree. It willbe appreciated that as the bending proceeds to the more sharply curvedend of the work, the withdrawal of the form block 25 can be slowed downin relation to the movement of the shoe so that the gap between the nipand the form block decreases. The result is that quite sharply curvedforms may be produced with workpieces having iianges of differentwidths, each workpiece being held in correct alignment with the formerthroughout the bending, and this has, as far as we are aware, previouslybeen impossible to achieve.

At the end of the bending operation the form-block 25 is fullyretracted. The main and auxiliary piston-andcylinder units 16, 21 on thearm 13 are then also retracted, the shoe being pulled 0E the work bymeans of the auxiliary shoe-controlled unit 21, and the finishedworkpiece removed. The arm 13 may then be swung back to its startingposition ready for the recommencement of the cycle to form anotherworkpiece.

It will be understood that the point at which the microswitch isoperated during bending to commence withdrawal of the forrn-block 25 isrelated to the distance, determined by the guide slots 27, to which theform-block is able to travel along the channel from the end of the shoe,and both these factors are dependent on, and decided according to, thenature of the curved form which it is desired to produce. l

Considerable modification of the machine as described above is possiblewithout departing from the scope of the invention. Thus, it would bepossible to arrange a form-block, or equivalent sliding work-holdingmember, to slide along the face of the shoe for holding a flat unilangedworkpiece in correct alignment with the male former, the anging andforming of the desired crosssectional shape of the workpiece, and thelengthwise bending thereof, being carried out in a single operation,instead of in two operations making use of preformed workpieces in thefinal stage as described above. The main diiiiculty, hitherto, in theflanging and lengthwise bending of workpieces in a single operation inone mathe bending operation in a direction to shift the place ofapplication of pressure to the workpiece away from the clamped end, asupplementary work-holding member, situated on the side of the nipbetween shoe and former towards which bending proceeds, to support theworkpiece against becoming mis-aligned with respect to the former whilebeing bent, said supplementary work-holding member being mounted on theshoe to slide along it, and actuating means operatively connected to thesupplementary work-holding member to move it while the workpiece isbeing bent along the shoe and workpiece ahead of the place ofapplication of pressure to the workpiece as said place is shifted,thereby keeping said member clear of the nip between shoe and former.

2. A metal-bending machine comprising a frame, a curved former on saidframe, means to hold a workpiece in place against the former forshaping, a shoe capable of v rolling upon the workpiece against theformer, pressurechine instead of employing two machines, or carrying outtwo runs on each workpiece in one machine, has been the control of theloose unclamped metal which, if left hanging with no support, will windsideways out of alignment with the former as the workpiece is bent;however, the present invention provides a means for holding theunclamped metal in control, and keeping the workpiece in correctalignment during the bending.

I claim:

1. A metal-bending machine comprising a frame, a

curved former'of said frame, means to hold a workpiece in place againstthe former for shaping, a shoe capable of rolling upon the workpieceagainst the former, pressure-applying means to press the shoe, workpieceand former together, means to effect rolling of the shoe against theformer, while the pressure is maintained, to shift the place ofapplication of pressure to the workpiece progressively along itssurface, the means to hold the workpiece in place serving to clampagainst the former one end of the part to be bent and the shoe movingduring applying means to press the shoe, workpiece and former together,means to effect rolling of the shoe against the former, while thepressure is maintained, to shift the place of application of pressure tothe workpiece progressively along its surface, the means to hold theworkpiece in place serving to clamp against the former one end of thepart to be bent and the shoe moving during the bending operation in adirection to shift the place of application of pressure to the workpieceaway from the clamped end, a supplementary work-holding member, situatedon the side of the nip between shoe and former towards which bendingproceeds, to support the workpiece against becoming misaligned withrespect to the former while being bent, which supplementary work-holdingmember is mounted on the shoe to slide along it in guide-ways providedalong the forming surface of the shoe and is spaced from said formingsurface sufficiently to allow a workpiece to lie between thesupplementary work-holding member and the shoe while being held closelyagainst the shoe by said member, and actuating means operativelyconnected to the supplementary work-holding member to move it while theworkpiece is being bent along the shoe and workpiece ahead of the placeof application of pressure to the workpiece as said place is shifted,thereby keeping said member clear of the nip between shoe and former.

y 3. A metal-bending machine comprising a frame, a curved former on saidframe having a profile that is convex in cross-section, means to hold aworkpiece in place against the former for shaping, a shoe capable ofrolling upon the workpiece against the former, which shoe has a formingsurface that is concave in the cross-sectional plane at right angles tothe plane of movement of the shoe relative to the former so as to t theconvex former profile, said forming surface thereby constituting achannel along the shoe, pressure-applying means to press the shoe,workpiece and former together, means to effect rolling of the shoeagainst the former, while the pressure ismaintained, to shift the placeof application of pressure to the workpiece progressively along itssurface, the means to hold the workpiece in place serving to clampagainst t-he former one end of the part to be bent and the shoe movingduring the bending operation in a direction to shift the place ofapplication of pressure to the workpiece away from the clamped end, asupplementary work-holding member situated on the side of the nipbetween shoe and former towards which bending proceeds to support theworkpiece against becoming misaligned with respect to the former whilebeing bent, which supplementary work-holding member is mounted in thechannel afforded by the forming surface of the shoe to slide along itand is spaced from said forming surface sufiiciently to allow aworkpiece to lie between said surface and the supplementary Work-holdingmember while being held closely against said surface by said member, andactuating means operatively connected to the supplementary work-holdingmember to move it while the workpiece is being bent along the shoe andworkpiece ahead of the place of application of pressure to the workpieceas said place is shifted, thereby keeping said member clear of the nipbetween shoe and former.

4. A metal-bending machine comprising a frame, a curved former on saidframe, means to hold a workpiece in place against the former forshapnig, a shoe capable of rolling upon the workpiece against theformer, pressureapplying means to press the shoe, workpiece and formertogether, means to effect rolling of the shoe against the former, whilethe pressure is maintained, to shift the place of application ofpressure to the workpiece progressively along its surface, the means tovhold the workpiece in place serving to clamp against the former one endof the part to be bent and the shoe moving during the bending operationin a direction to shift the place of application of pressure to theworkpiece away from the clamped end, a supplementary work-holdingmember, situated on the side of the nip between shoe and former towardswhich bending proceeds, to support the workpiece against becomingmisaligned with respect to the former while being bent, saidsupplementary work-holding member being mounted on the shoe to slidealong it, and a piston-andcylinder unit for actuating the supplementarywork-holding member, the cylinder of which is pivotally mounted inbrackets on the end of the shoe and the piston rod of which is pivotallyconnected to the supplementary workholding member, said piston andcylinder unit serving to move said member while the workpiece is beingbent along thc shoe and workpiece ahead of the place of application ofpressure to the workpiece as said place is shifted, thereby keeping saidmember clear of the nip between shoe and former.

5. A metal-bending machine comprising a frame, a curved former on saidframe, means to hold a workpiece in place lagainst the former forshaping, a shoe capable of rolling upon the workpiece against theformer, pressureapplying means to press the shoe, workpiece and formertogether, means to effect rolling of the shoe against the former, whilethe pressure is maintained, to shift the place of application ofpressure to t-he workpiece progressively along its surface, the means tohold the workpiece in place serving to clamp against the former one endof the part to be bent and the shoe moving during the bending operationin a direction to shift the place of application of pressure to theworkpiece away from the clamped end, a supplementary work-holding membermounted to slide along the shoe on the side of the nip between shoe andformer towards which bending proceeds to support the workpiece againstbecoming misaligned with respect to the former while being holdingmember has projections sliding in guide-slots extending along the-forming surface of the shoe to guide the supplementary work-holdingmember in its movements, and actuatin 7 means operatively connectedtothe supplementary work-holding member to move it while the workpiece isbeing bent along the shoe and workpiece ahead of the place ofapplication of pressure to the workpiece as said place is shifted,thereby keeping said member clear ofthe nip between shoe and former.

6. A metal-bending machine comprising a frame, a curved former on saidframe having a prole that is couvex in cross-section, means to hold aworkpiece in place against the former for shaping, a shoe capable ofrolling upon the workpiece against the former, which shoe has a formingsurface that is concave in the cross-sectional plane at right angles tothe plane of movement of the shoe relative to the former so as to fitthe convex former prole, said forming surface thereby constituting achannel along the shoe, pressure-applying means to press the shoe,workpiece and former together, means to elect rolling of the shoeagainst the former, while the pressure is maintained, to shift the placeof application of pressure to the workpiece progressively along itssurface, the means to hold the workpiece in former one end of the partto be bent and the shoe movbent, which supplementary workplace servingto clamp against the ing during the bending operation in a direction toshift the place of application of pressure to the workpiece away fromthe clamped end, a supplementary work-holding member situated on theside of the nip between shoe and former towards which bending proceedsto support the workpiece against becoming mis-aligned with respect tothe former while being bent, which supplementary workholding member' ismounted in the channel afforded by the forming surface of the shoe toslide along it and has projections sliding in guide-slots extendingalong said forming surface to guide said member in its movements, saidsupplementary work-holding member being spaced from said forming surfacesufficiently to allow a workpiece to lie between said surface and thesupplementary work-holding member while being held closely against saidsurface by said member, and actuating means operatively connected to thesupplementary work-holding member to move it while the workpiece isbeing bent along the shoe and workpiece ahead of the place ofapplication of pressure tothe workpiece as said place is shifted,thereby keeping said member clear of the nip between shoe and former.

7. A metal-bending machine comprising a frame, a curved former on saidframe having a profile that is con- Vex in cross-section, means to holda workpiece in place against the former for shaping, a shoe capable ofrolling upon the workpiece against the former, which shoe has a formingsurface that is concave in the cross-sectional plane at right angles tothe plane of movement of the shoe relative to the former so as to fitthe convex former profile, said forming surface thereby constituting achannel along the shoe, pressure-applying means to press the shoe,workpiece and former together, means to etect rolling of the shoeagainst the former, while the pressure is maintained, to shift the placeof application of pressure to the workpiece progressively along itssurface, the means to hold the workpiece in place serving to clampagainst the former one end of the part to be bent and the shoe movingduring the bending operation in a direction to shift the place ofapplication of pressure to the workpiece away from the clamped end, asupplementary work-holding member situated on the side of the nipbetween shoe and former towards which bending proceeds to support theworkpiece against becoming mis-aligned with respect to the former whilebeing bent, which supplementary work-holding member is mounted in thechannel afforded by the forming surface of the shoe to slide along itand has projections sliding in guide-slots extending along said formingsurface to guide said member in its movements, said supplementarywork-holding member being spaced from said forming surface sufiicientlyto allow a workpiece to lie between said surface and the supplementarywork-holding member while being held closely against said surface bysaid member, and a piston-and-cylinder unit for actuating thesupplementary work-holding member, the cylinder of which is pivotallymounted in brackets on the end of the shoe and the piston rod of whichis pivotally connected to the supplementary work-holding member, saidpiston and cylinder unit serving to move said member while the workpieceis being bent along the shoe and workpiece ahead of the place ofapplication of pressure to the workpiece as said place is shiftedthereby keeping said member clear of the nip between shoe and former.

References Cited in the tile of this patent UNITED STATES PATENTS1,379,858 Gail May 31, 1921 1,462,315 Akey July 17, 1923 1,982,164Hoener Nov. 27, 1934 2,142,443 Goin Ian. 3, 1939 2,255,867 Wisckol Sept.16, 1941 2,636,537 Redman Apr. 28, 1953 2,680,467 Redman June 8, 1954

